Redundant network interface for ethernet devices

ABSTRACT

A redundant network interface for ethernet devices is disclosed. The redundant network interface provides connections between one or more Ethernet devices and two or more independent networks. The redundant network interface device also tests an active primary Ethernet connection path, and when a failure or inactive path is detected, the redundant network interface device reroutes the messages to alternate communication path.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates generally to a network switch for communicationsnetworks, and more particularly to a redundant network switch which isable to interface with and segregate two or more independent Ethernetnetworks. A method of using the redundant network switch interfacedevice is also presented.

2. Related Art

It is often desirable to form multiple connections to devices on anEthernet network to enhance reliability, or to connect one or moreEthernet device(s) to two independent networks. The vast majority ofEthernet devices have only a single Ethernet port, and/or either limitedor no capabilities to make multiple, independent connections.

Local Ethernet devices are commonly connected to an Ethernet network byuse of a device known as an Ethernet hub or network switch. Thesedevices typically make the required connections with no regard tosegregation or restriction of network traffic. There are significantlimitations to the usefulness of using these network switches to makeconnection to independent networks. These limitations include, interalia:

a) Unmanaged network switches pass messages from one network to theother, thus removing independence of the networks. This unwanted trafficincreases network loading; can breach security through the undesirabletransmission of messages; and can cause network conflicts if, forexample, duplicate addressing is in use on the independent networks.

b) In the case of applications utilizing redundant network paths,unmanaged network switches could send messages back to network nodesthat have received this message already from another path. Thisundesired event could cause unacceptable confusion on the network.

c) In redundant network schemes it is desirable to know when a failurein one of the network paths occurs so that a repair can be made. Networkswitches do not identify the path of the message for this purpose.

d) While many of these limitations can be overcome with a managednetwork switch or router, these complex devices require configurationand careful network planning. Further, the addition of new devices onthe network or changes in the network topology can requirereconfiguration for continued operation.

Accordingly, there exists a need for a simplified redundant networkinterface, which is capable of solving the above-mentioned limitationsrelated to network switches for making connections to, as well as toproviding segregation and redundancy for, independent networks.

SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to overcome the aboveshortcomings related to segregation and redundancy for independentnetworks, by providing a method and apparatus for a redundant networkinterface embodied in a network switch which is able to interface withand segregate two or more independent Ethernet networks.

This invention disclosed herein is a network switch which is easilyconfigured by a user possessing limited technical knowledge. Thesimplicity of this invention enhances reliability (through itssimplicity), reduces installation time and skill level required, makesit practical to swap these devices when repairs are necessary, and makesit possible to view or control the flow of network traffic throughcommercially available industrial controllers or software.

The invention is built upon the observation that it is desirable for oneor more Ethernet devices to communicate to each of two or moreindependent networks through “uplink” ports, and that as long as theuplink ports are not permitted to send messages between themselves,independence (i.e., segregation) of the networks is maintained. Thisembodiment uses an unmanaged network switch that is given a special ruleto never pass messages from one uplink port to any other port designatedas an uplink port. In this way, segregated traffic on the independentnetworks is maintained. An added benefit of this embodiment is thatdevices connected to the ports other than the uplink ports (i.e., localports), may freely communicate amongst themselves, without restriction,and with the added benefit of improved network bandwidth by segregatinglocal network traffic from wide area network traffic. All other benefitsof the unmanaged network switch are maintained, such as avoidance ofcollisions, and limitation of broadcast message bandwidth.

In a first general aspect, the present invention provides acommunications network comprising: at least two independent Ethernetnetworks, including a primary Ethernet network and an alternate Ethernetnetwork, said independent Ethernet networks receiving information fromone or more local network devices, and at least one network switch,wherein said network switch selectively enables communication betweenone of said primary network and said alternate network and said localnetwork devices, and wherein said network switch selectively does notenable communication between said primary network and said alternatenetwork.

In a second general aspect, the present invention provides a method ofproviding redundancy in a communications network, said methodcomprising: providing at least two independent networks, including aprimary network and an alternate network, said independent networks eachadapted to receive information from at least one local network device;providing at least one network switch, wherein said network switchselectively enables communication between one of said primary networkand said alternate network and said local network device, and whereinsaid network switch does not enable communication between said primarynetwork and said alternate network.

In a third general aspect, the present invention provides a networkswitch comprising: a first plurality of communication ports, said firstplurality of communication ports coupled to at least two independentnetworks, including a primary network and an alternate network; a secondplurality of communication ports, said second plurality of communicationports coupled to one or more local network devices; a plurality ofcommunication path combinations available in said network switch,wherein each said communication path combination is selected from thegroup consisting of: the primary network to a first local networkdevice; the primary network to a second local network device; thealternate network to the first local network device; the alternatenetwork to the second local network device; and the primary network tothe alternate network; and a system for preventing communication betweensaid primary network and said alternate network through said networkswitch.

In a fourth general aspect, the present invention provides a method ofnetwork communication comprising: providing a first plurality ofcommunication ports, said first plurality of communication ports coupledto at least two independent networks, including a primary network and analternate network; providing a second plurality of communication ports,said second plurality of communication ports coupled to one or morelocal network devices; providing a plurality of communication pathcombinations available in a network switch, wherein each saidcommunication path combination is selected from the group consisting of:a primary network to a first local network device; the primary networkto a second local network device; an alternate network to the firstlocal network device; the alternate network to the second local networkdevice; and the primary network to the alternate network; and providinga system for preventing communication between said primary network andsaid alternate network through said network switch.

In a fifth general aspect, the present invention provides a localnetwork device comprising: at least one first communication port, saidfirst communication port adapted to communicate with a network switch;said local network device including at least one status signal; saidstatus signal monitored by said network switch.

In a sixth general aspect, the present invention provides a method ofcommunicating between a local network device and a network, said methodcomprising: providing at least one local network device and at least onenetwork; providing at least one communication port of said local networkdevice, said communication port adapted to communicate with said networkvia a network switch; providing said local network device with at leastone status signal indicative of the operational status of the localnetwork device; and providing said network switch with means formonitoring said status signal.

In a seventh general aspect, the present invention provides a computerprogram product, comprising: a computer usable medium having a computerreadable program code stored therein for causing a communication pathfailure to be detected, the computer readable program code comprising:first computer readable program code for causing a computer to detectfailures in at least one communication path; second computer readableprogram code for causing the computer to effect changes in the routingof said communication paths; and third computer readable program codefor causing the computer to prevent establishment of specificcommunication paths.

The foregoing and other features and advantages of the invention will beapparent from the following more particular description of embodimentsof the invention. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary, butare not restrictive, of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and inventive aspects of the present invention will becomemore apparent upon reading the following detailed description, claimsand drawings, of which the following is a brief description.

FIG. 1 is a schematic view of a communication network including aredundant network switch in accordance with an embodiment of the presentinvention.

FIG. 2 is a schematic view of a redundant network switch in accordancewith an embodiment of the present invention.

FIG. 3 is a schematic view of a redundant network switch in accordancewith an embodiment of the present invention.

FIG. 4 shows a schematic representation of a network system including anetwork switch used manage two redundant paths in accordance with anembodiment of the present invention.

FIG. 5 shows a schematic representation of a network system includingInternet connections in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following is a detailed explanation of the structure and method fora method and apparatus for a redundant network switch which is able tointerface with and segregate two or more independent networks. For thepurposes of illustration, these networks will be referred to as Ethernetnetworks herein. It should be noted that the same reference numbers areassigned to components having approximately the same functions andstructural features in the following explanation and the attacheddrawings to preclude the necessity for repeated explanation thereof.

According to a general illustrative embodiment of the present invention,shown schematically in FIG. 1, the illustrative system 100 describedherein includes a network switch 130 which will function as an elementin a larger network, for example, in an Ethernet network. An Ethernetnetwork, as discussed herein including VLAN (to be discussed infra), isa local area network wherein data is broken into packets and transmittedwithin a network which network contains switch apparatus capable ofrerouting the transmitted data. Each packet is transmitted, and arrivesat its destination without colliding with any other packet. The firstcontention slot after a transmission is reserved for an acknowledgepacket. A node is either transmitting or receiving at any instant.Moreover, the Ethernet networks discussed herein are characterized bycertain unique Ethernet characteristics known to those skilled in theart, namely the use of an Ethernet frame structure; an unreliable andconnectionless service to a network layer; baseband transmission withManchester encoding; and use of a Carrier Sense Multiple Access withCollision Detection (CSMA/CD) multiple access algorithm. An Ethernetnetwork will be discussed as relating to the illustrative embodiment forconvenience sake, but this discussion is not meant to be limited toEthernet networks only, nor to any particular type of network.

The Ethernet switches disclosed and claimed herein are as used inEthernet systems by persons of ordinary skill in the art. The knownEthernet switches include, inter alia, two characteristics which areparticularly relevant. First, MAC-based ports with I/O data framebuffers effectively isolate the port from data traffic being sent at thesame time to or from other ports on the Ethernet switch. Second,multiple internal data paths allow data frames to be transferred betweendifferent ports at the same time. Because each port provides access to ahigh-speed network bridge (i.e., the switch), the collision domain inthe network is reduced to a series of small domains in which the numberof participants is reduced to two, namely the switch port and theconnected Network Interface Card (NIC).

The first illustrative system 100 utilizes a feature which may be foundin network switches, especially Ethernet switches. This feature isreferred to as a Virtual Local Area Network (VLAN). A VLAN grouprepresents a logical grouping of two or more nodes which are notnecessarily on the same physical network segment, but which share thesame network number or address. VLAN groups are often associated withswitched Ethernet. Utilizing the VLAN group feature permits restrictionof communications traffic to only selected communication ports, so thatthe communications traffic can be restricted, for example, to authorizedgroups of users or to specific devices.

Referring to FIG. 1, a network switch 130 is shown. Network switch 130includes an embedded microprocessor 170, which is programmed for thisapplication, and which is operatively connected to the first and secondnetwork (i.e., uplink) ports 110, 120, respectively, of the networkswitch 130. Embedded microprocessor 170 is also operatively connectedinternally to the first, second and third device ports (i.e., localports) 140, 150, 160, respectively, of the network switch 130. Localdevices (not shown) connected to the device ports 140, 150, 160,include, inter alia, input and/or output devices, switches, transducers,etc.

Two or more restricted VLAN groups are configured by appropriatesoftware programmed in the embedded microprocessor 170. The first VLANgroup could include, for example, communication from first network port110 to first, second and third device ports 140, 150, 160, respectively,via embedded microprocessor 170. Thus, the first VLAN group wouldconnect the first network port 110 to any or all of the first, second,and third device ports 140, 150, 160.

Similarly, the second VLAN group would include, for example,communication from the second network port 120 to any or all of thefirst, second, and third device ports 140, 150, 160, via embeddedmicroprocessor 170.

In addition, the embedded microprocessor 170 is included in both VLANgroups so that the microprocessor 170 can access all ports, both thenetwork ports 110, 120 and the device ports 140, 150, 160 for diagnosticpurposes. However, what is specifically prohibited, by the novel networkswitch disclosed herein, is inclusion of both network ports 110, 120within the same VLAN group. Thus, communication through the networkswitch 130 between a first independent network 105 coupled to firstnetwork port 110 and a second independent network 115 coupled to secondnetwork port 120 is not allowed. The network switch 130, as used in thisarrangement, further provides network redundancy should the first 105 orsecond 115 independent network fail. Networks 105, 115 may include,inter alia, network host devices, routers, servers, and the like.

The embedded microprocessor 170 is assigned an Internet Protocol (IP)address so that the embedded microprocessor can be addressed from meansexternal to the network switch 130. Network configuration information,such as, inter alia, a configuration chart, is loaded into the embeddedmicroprocessor 170 with the appropriate connection rules, including theprimary and an optional secondary or alternate connection for eachdevice port 140, 150, 160, as well as the IP or Media Access Control(MAC) addresses of network devices that are to be monitored. The use ofboth the IP and the MAC addresses allows both IP (e.g., TCP/IP(Transmission Control Protocol/Internet Protocol) and other Ethernetprotocols, such as, inter alia, IEEE 802.2 LLC (Logic Link Control) tobe implemented.

Periodically, a test message (such as, inter alia, a Packet InterNetGroper (PING)) is sent to each network device listed on theconfiguration chart to determine the operational status of the portionof the network connected between the network switch 130 and whateverdevices are connected to the device ports 140, 150, 160 or the networkports 110, 120. If a station (e.g., a network device) fails to respond,then a failed or inactive network has been found, and a status bit isset accordingly in the embedded microprocessor 170. Optionally, one ormore “retries” can be configured, and the timing of the tests can beconfigured by the user via a programmable device or other system forprogramming an embedded microprocessor as is known in the art. Upondetection of a failure to communicate over a particular port of thenetwork switch 130, or to an inactive device, the embeddedmicroprocessor 170 can command the network switch 130 to reconfigure theVLAN group so as to reroute traffic to a backup path which has beenpreviously defined by the user. That is, software programmed in theembedded microprocessor 170 instructs the network switch to produce anew VLAN group configuration, which does not include the inactivenetworks or devices, but which does include active networks or devices.The new VLAN group configuration will exclude the network path which hasbeen determined to be defective. The VLAN group configurations may bebased on one of the following implementations, or a combination of them:a port-based VLAN; a MAC address-based VLAN; or a protocol-based VLAN.Further, the above VLAN group configurations may use either knownimplicit methods or explicit methods to indicate membership in aparticular group when a signal travels between switches.

In this manner, this network switch 130 can be used to connect two (ormore) independent networks to the same local device, by keeping twosegregated VLAN groups in use, or by creating a backup system byswitching the VLAN group configuration upon the failure of a networkpath. One advantage of this scheme is that the embedded microprocessor170 has continuous access to all ports, even if they are not in activeuse. This enables a continuous test of all communication paths andverification of their readiness for use.

Referring to FIG. 2, a second illustrative system 200 depicts a morespecific example including an Ethernet network switch 230 having twoindependent network ports 210, 220, respectively, and six device ports240, 242, 250, 252, 260, 262, respectively. A ninth port 280 is used toconnect to internal embedded microprocessor 270, which is added to thisnetwork switch 230 for the purposes of implementing this invention.

The number of uplink ports and device ports is not limited to theseparticular amounts. Rather, these amounts are intended to be used forillustrative purposes only. The second illustrative embodiment 200 issimilar to a commercially available Ethernet store-and-forward networkswitch, such as, inter alia, a SIXNET switch, part number ET-GT-9ES-1,which has nine such Ethernet ports.

The embedded microprocessor 270 within this network switch 230 may be adedicated microprocessor, or it may be part of the core circuitry foundin an existing module, such as, for example, a SIXNET EtherTRAK I/Omodule (i.e., part number ET-16DI2-H). The core circuitry of this SIXNETmodule includes an embedded microprocessor (such as, inter alia, anAtmel Mega 103 microprocessor). Network switch 230 may also includeperipheral circuitry (not shown) that includes a network port 210, (suchas, inter alia, an Ethernet port) as well as other components (notshown) needed to make the embedded microprocessor 270 function properly.Program software and data are stored in memory related to the embeddedmicroprocessor 270. Henceforth, this embedded microprocessor 270 and itsrelated peripheral circuitry will be referred to as the CentralProcessing Unit (CPU) 235. Hence, the network 230 comprises the CPU 235,and the CPU 235 comprises the embedded microprocessor 270.Alternatively, the CPU 235 may also be incorporated in an Ethernetswitch IC.

The network port on the CPU 235 is connected to the ninth (internalonly) port 280 on the network switch 230 through the appropriateinterface components (not shown). Programming or software is loaded intothe CPU 235 such that, upon initialization of the network switch 230,software instructions will be loaded into the embedded microprocessor270 or into the Ethernet switch IC to establish the VLAN groupconnections described below. The VLAN group connections will beimplemented using either existing unused features of the Ethernet switchIC that implement the network path configurations, or by using therequired features of other similar Ethernet switch ICs.

By default, two VLAN groups (i.e., the CPU 235 and clusters of portsthat are permitted to communicate with each other) are established inthe network switch 230. One VLAN group includes all of the local deviceports 240, 242, 250, 252, 260, 262, the CPU 235, and the first networkport 210, and is primarily intended to provide the first network port210 with unrestricted communications with the local device ports 240,242, 250, 252, 260, 262 and the CPU 235. The second VLAN group includesall local device ports 240, 242, 250, 252, 260, 262, the CPU 235, andthe second network port 220, and is primarily intended to provide thesecond network port 220 with unrestricted communication with the localdevice ports 240, 242, 250, 252, 260, 262 and the CPU 235. The localdevice ports 240, 242, 250, 252, 260, 262 in the default configurationwill be permitted to communicate with one another, and the CPU 235 willbe permitted to talk to all ports. This functionality will be assumed inthis document and the details of it are not important to describing theinvention, but may in the most efficient embodiment, suggest theestablishment of additional VLAN group connections. It is important tonote that in none of the VLAN group connections is the first networkport 210 permitted to exchange messages with the second network port220.

In this basic configuration, no further intelligence is needed to permiteach of the network ports 210, 220 free access to all of the localdevice ports 240, 242, 250, 252, 260, 262, as if it were the onlynetwork port in use. Since the two network ports 210, 220 cannotcommunicate with each other, they are invisible to each other, and thenetwork switch 230 functions as if it were two independent networkswitches, each with a connection from its network 205, 215 to all of thelocal devices 240, 242, 250, 252, 260, 262 (or subsequent groups oflocal devices through additional downstream network switches) connectedto local device ports 240, 242, 250, 252, 260, 262. In thisconfiguration, redundancy is achieved by having two independent networks205, 215 being able to access the local devices 240, 242, 250, 252, 260,262 connected to this network switch 230.

By way of example, two computers (not shown) connected to the networkports 210, 220 on this network switch 230 could each poll all of thelocal device ports 240, 242, 250, 252, 260, 262. These two computers canhave programming that causes said local device ports to monitor thequality of the various network connections, and also the quality of thedata that travels over the network connections. These two computers canestablish their own rules for handling the loss of data, orcommunications paths, by arbitrating the behavior of the programsrunning in these two computers, possibly using an independentcommunications link between the two computers to signal each other. Thiscommunications link would be exclusive of the VLAN groups' network pathsto which each of the two computers is also connected.

The CPU 235 in this network switch 230 may be configured from anexternal computer (e.g., a configuration tool) through an Ethernetconnection from any port on the network switch 230. Initialization ofthe CPU 235 itself, including the establishment of an IP address (i.e.,the 32-bit host address defined by the Internet Protocol) for the CPU235, is accomplished in a known manner usually employed to talk to aninput/output (I/O) module, such as, inter alia, an EtherTRAK I/O module,which is a commercially available device, and which is well documentedin its user manual. When the quality of specific network connections isdetermined, the resulting status flags will be stored in discrete I/Oregisters in the CPU 235.

Another aspect of the system 200 is the ability to set test pollingcharacteristics, including the frequency of polling, the number of timesto retry before reporting a failure, and the delay time to wait for aresponse to the test message (i.e., the ping), before assuming thatcommunication has been lost, and therefore initiating a retry or reportof a failure. In real-time industrial systems, the response time of thesystem can be important. The ability to control these parameters andthereby enable adequately responsive behavior without overly burdeningthe network with test messages or inadvertent failure reports isimportant to the overall performance of the system to which thisinvention is applied. Typically, in practical systems, polling can beset in the range of a few milliseconds to many seconds, response delaysfrom 5 milliseconds to many seconds, and maximum retry attempts can varyfrom one to five. For example, if an Internet connection is present inthe path of a test, the response to a ping can take seconds to bereceived.

So far what has been described is an embodiment in which two independentnetworks are managed passively, with the network management of anyredundancy in communication paths occurring external to the networkswitch. The network management may or may not use the status informationavailable in the I/O registers. The second method of configuration,however, utilizes the communication test results to switch betweenalternate network paths in the event of failure of one of the paths.This second method of configuration is discussed with respect to theillustrative embodiment of the system 300 in FIG. 3.

In system 300, the configuration of the virtual network connections isrestricted to direct network messages from one or more device ports 340,350, 360 to a single network port 310, which is designated the primarynetwork path for that particular communication scheme. The second path,not presently in use, will be referred to as the secondary or alternatenetwork path. This second path would be between the one or more deviceports 340, 350, 360 and single network port 320. In order to permitconstant testing of both the primary and the secondary path, virtualconnections between the CPU 335 and the primary and secondary paths areestablished. A virtual connection is a connection or path through anetwork. The word “virtual” is used to indicate that the connection islogical rather than physical. The virtual connection is established whenthe Ethernet switch IC is instructed to forward packets to a particularport. The virtual connection used herein make the paths independent ofthe configuration presently in use, which may be blocking networktraffic to either of the network ports 310, 320 depending on the resultsof ongoing communication tests.

In this case, the two communication paths may or may not be connected tothe same Ethernet device. This is not of primary importance, as long asboth paths are capable of passing the message to the intended receivingstation. The two paths are not in use at the same time (to avoidconfusion on the network) except by the CPU 335, which may use uniqueaddresses for each path. When a switch over occurs, the receiving device(not shown) connected to a device port 340, 350, 360 is capable ofaccepting the message from the alternate path and routing it to itsintended destination.

The CPU 335 may use distinct MAC and TCP/IP addresses for each networkport 305, 315. Distinct MAC addresses are required to prevent otherEthernet switches from erroneously updating their connection tables.With a single MAC address for the CPU 335, if both the primary andsecondary paths traverse the same Ethernet switch, it would alwaysdirect messages to the CPU 335 out of the port of the most recently usedpath, but the CPU 335 needs to use both paths. Distinct TCP/IP addressesmay be needed since the IP address generally determines which interfaceor port to use when sending a message.

When a failure of a primary communication path is detected, the CPU 335directs the configuration switch 370 to reconfigure the virtualconnection groups in a manner prescribed in the configuration dataloaded into the CPU 335. As a practical embodiment, options will bepresented as part of the configuration rules to either:

-   -   1) have the device port(s) 340, 350, 360 remain connected to the        secondary path once a failure of the primary path is detected;    -   2) switch the device port(s) 340, 350, 360 back and forth        between the two paths each time a failure of the path in use is        detected; or    -   3) switch the device port(s) 340, 350, 360 back to the primary        path if a subsequent test demonstrates that the primary path has        been restored or otherwise has once again become capable of        proper operation.

These three scenarios can be illustrated with reference to FIG. 3,wherein it is assumed that network port 310 is the primary port andnetwork port 320 is the secondary port. Also, CPU 335 directsconfiguration switch 370 which includes a first switch 317 and a secondswitch 318. As an initial condition, the primary path would beoperating, so that operational connections exist between the first orprimary network port 310 and the device port(s) 340, 350, 360. In thefirst scenario, a failure in the primary path connected to primarynetwork port 310 is detected. Therefore, second switch 318 closes, whilefirst switch 317 opens. The result is that the device ports 340, 350,360 are now connected to the operative network port 320.

In the second scenario, the situation just described would occur whenthe primary path fails. Then, assuming the primary path is restored andthe secondary path fails, device ports 340, 350, 360 are connected tothe primary network port 310 by the closing of first switch 317 and theopening of second switch 318. Thus, communication between the deviceports 340, 350, 360 and the primary network is restored. Then, if theprimary network again fails, the switching of scenario 1 above isrepeated. Finally, these switching scenarios may be repeatedly performedas one network is restored and the other fails.

The third scenario assumes that, while the primary path has failed andthe network is operating on the secondary path, and the primary path hasbeen subsequently restored. Configuration switch 370 may be, inter alia,an electronic routing means, a switching means, a steering means, etc.,which temporarily stores and holds data packets. For clarity in thisdiscussion, the configuration switch 370 is depicted as a mechanicalswitch. However, this embodiment is for clarification, and is not meantto be limiting. In this case, the configuration switch 370 may revert tothe primary path by effectively closing switch 317 and effectivelyopening switch 318, in response to preprogrammed instructions to alwaysuse the primary path when is available. In this scenario, the secondarypath is maintained as the spare path for use whenever the primary pathis not available, and only when the primary path is not available.

Some Ethernet devices, including the store-and-forward switchincorporated into the ET-GT-9ES-1 and used in the second illustrativeembodiment this invention, remember the network path used to communicatewith particular Ethernet devices as a means to efficiently routemessages over only the required network segment. Store-and-forwardmessaging, or message switching, is a known type of message passingsystem wherein a complete message is received before it is passed on tothe next node. These store-and-forward devices remember the location ofan Ethernet device by detecting the source of a message arriving on aport (i.e., the detection of the source MAC address in a transmittedEthernet message packet). In situations in which other local devices aresending messages to a particular local device that will not send amessage until requested to do so, the network switch will not detect thechange in path for perhaps several minutes, when the seemingly unusedpath ages off of the active list of connections.

Additional means may be employed to rapidly update the routinginformation for other Ethernet network switches connected to theredundant network switch of the present invention. For example, FIG. 4shows a schematic representation of a network system 400 wherein anetwork switch 410 is used manage two redundant paths 415, 420 so thatcontroller 430 can always talk to device 435 provided at least one ofthe paths 415, 420 is operational. Network switch 410 also includesEthernet switch 440. Peripheral circuitry (not shown), associated withan embedded microprocessor includes an Ethernet port and othercomponents needed to make the microprocessor function. Program and datamemory for the microprocessor may be included within the integratedcircuit itself. For the purposes of this discussion, the microprocessorand its related peripheral circuitry will be referred to as CPU 425. CPU425 may also be part of Ethernet switch 440, or they may be separatedevices.

An Ethernet port on the CPU 425 is connected to the an internal-onlyport 414 of the Ethernet switch 440 via appropriate interfacecomponents. Programming is loaded into the CPU 425 that, uponinitialization of the network switch 410, will load instructions intothe Ethernet IC or switch 440 to establish the VLAN group connectionsdescribed infra. The VLAN group connections may be implemented eitherusing existing unused features of the Ethernet switch IC that implementnetwork path configuration, or using the required features of othersimilar Ethernet switch ICs.

Device port 411 is connected to network port 412 and port 441 isconsidered by the Ethernet switch 440 to be in use. If first path 415 isin use, then fails, and the network switch 410 determines that secondpath 420 must now be used, merely reconfiguring the virtual groupconnections in the network switch 410 to connect device port 411 fromthe network port 412 to network port 413 will not immediately restorecommunications. The Ethernet switch 440 still considers the controller430 (e.g., an input/output device) as connected using the first path415, which the device 435 is not allowed to use. Ethernet switch 440still considers first path 415 as the connection to the device 435, butany messages sent via that (failed) first path 415 will be rejected bythe Ethernet switch 440 in the network switch 410. To avoid thissituation, the network switch 410 can be configured to send specialmessages from the CPU 425 to one or more specific network devices (e.g.,device 435) after a switch over in network ports 412, 413 occurs. Themessages and the resulting responses will inform the Ethernet switch 440that port 442, instead of port 441 must be used. Each message andresponse can update the Ethernet switch 440 for one MAC address (i.e.,the hardware address of a device connected to the shared network) thatis connected to the network switch 410 via a device port 411 and onecontroller 430 connected via a network port 412, 413. In the example,the CPU 425 must send one message via internal port 414 to update thenetwork switch's internal connection tables as follows:

-   -   1. A message is sent by the CPU 425 to the controller 430 using        the MAC and IP addresses of the device 435 as the source, and        the broadcast MAC address (i.e., so that the transmission is        sent to multiple, unspecified recipient devices, and these        devices are always willing to receive the transmission) and the        IP address of the controller 430 as the destination. A signal        from the controller 430 indicating successful receipt of the        message informs Ethernet Switch 440 that the device 435 is now        using the second path 420. The broadcast address is used to        ensure the message is sent out to all ports, including the        second network port 413.    -   2. The reply (or any subsequent message) from the controller 430        instructs the Ethernet switch 440 in the network switch 410 that        the controller 430 is using the second path 420.

The messages for each device 435 or controller 430 after the firstmessage would be similarly transmitted, but if there are more devicesthan controllers, the broadcast MAC address can be changed to thespecific address of one of the controllers, or even an unused address,to reduce network traffic. Note that the MAC addresses used in the aboveexample are the MAC addresses associated with the IP address of therecipient device as seen by the network switch 410, and which may,alternatively, be the MAC address of an IP gateway that is used tocommunicate with the IP address. As used herein, the term “gateway”refers to any one of the following, inter alia: a “protocol converter”to connect networks using different protocols; a “router” to connect twobroadcast networks at a network layer; or a mail gateway (i.e., anapplication layer gateway).

One final note, during the time between the failure of a communicationpath and the redirection of network messages to an alternative path,message packets will likely be lost. It is assumed in this embodiment,that so-called “robust” communications systems (i.e., the communicationssystems have an ability to recover from a whole range of exceptionalinputs and other abnormal situations in a given environment) existbetween all critical network paths, and that the robust communicationssystems will, on their own initiative, send retries as needed. It isalso assumed for a successful embodiment that the test-and-switch-overparameters (i.e., those parameters programmed into the network switchwhich control when a network switch operation is necessary to changepaths, and how the switch of the paths is accomplished) configured intothis inventive network switch are sufficiently responsive as to becompatible with the dynamics of the messaging requirements of theoverall network system. These details are the responsibility of theindividual that specifies the network system and configures theapplication specific parameters into the CPU 425 of this invention.Operation of CPU 425 is similar to that of CPU 235 discussed supra.

FIG. 5 shows a schematic representation of a network system 500including Internet connection modules 510, 520 in accordance with anembodiment of the present invention. Either or both of Internetconnection modules 510, 520 may be present. In this embodiment, networkswitch 505 includes ethernet switch 506, network ports 501, 502 anddevice ports 503, 504. Network switch 505 functions as network switch410 described supra, except in this embodiment, the network switch 505is part of an overall network system 500 which includes one or moreInternet connection modules 510, 520. A series of n network connectionmodules 530, 531, 532 are connected to network ports 501, 502 of networkswitch 505 via at least one Internet connection module 510. Networkmodules 530, 531, 532 provide access to existing networks. Similarly, aseries of m local devices 540, 541, 542 are connected to device ports503, 504 of network switch 505 via at least one Internet connectionmodule 520. The number (i.e., n and m) of the various elements shown isintended for illustrative purposes only, and is not intended to be takenas limiting.

Embodiments of the present invention have been disclosed. A person ofordinary skill in the art would realize, however, that certainmodifications would come within the teachings of this invention. Forexample, rather than the single device embodiment discussed hereinregarding FIG. 4, the present invention also encompasses embodimentswherein there are a plurality of devices and/or a plurality of networkswitches. Other alternative embodiments could include a plurality ofnetwork switches connected in series or in parallel with each other, thecombined conglomeration of network switches then connected to aplurality of network segments, etc. Therefore, the following claimsshould be studied to determine the true scope and content of theinvention.

1. A communications network comprising: a primary Ethernet network; analternate Ethernet network, wherein said primary Ethernet network isindependent from said alternate Ethernet network, and wherein saidprimary Ethernet network is not connected to said alternate Ethernetnetwork; and a network switch comprising a central processing unitinternal to said network switch, wherein said central processing unit isdirectly connected to said primary Ethernet network and said alternateEthernet network, wherein said central processing unit is configured toprevent communications between said primary Ethernet network and saidalternate Ethernet network, wherein said central processing unitcomprises an embedded microprocessor, wherein said primary EthernetNetwork is configured to be connected to at least one local networkdevice through said embedded microprocessor, wherein said alternateEthernet network is configured to be connected to said at least onelocal network device through said embedded microprocessor, wherein saidat least one local network device is not located within said primaryEthernet network or said alternate Ethernet network, wherein saidembedded microprocessor comprises a configuration chart internal to saidembedded microprocessor, wherein configuration chart comprisesconnection rules associated with said primary Ethernet network and saidalternate Ethernet network, wherein said configuration chart comprises aprimary connection and an optional secondary connection for said atleast one local network device, wherein said configuration chartcomprises an Internet protocol (IP) address or media access control(MAC) address of said at least one local network device, wherein saidprimary Ethernet network is configured to receive information from saidat least one local network device and said network switch, wherein saidalternate Ethernet network is configured to receive said informationfrom said at least one local network device and said network switch,wherein said information is routed through said embedded microprocessor,wherein said network switch selectively enables communication betweensaid primary Ethernet network and said at least one local network deviceor between said alternate Ethernet network and said at least one localnetwork device, wherein said primary Ethernet network in combinationwith said central processing unit and said at least one local networkdevice forms a first virtual local area network (VLAN), wherein saidalternate Ethernet network in combination with said central processingunit and said at least one local network device forms a second VLAN,wherein said network switch does not enable communication between saidprimary Ethernet network and said alternate Ethernet network, whereinsaid microprocessor is configured to send a test message to said atleast one local network device in order to determine an operationalstatus of said primary Ethernet network, wherein said communicationsnetwork is configured to set a status bit in said microprocessor if saidoperational status indicates that said primary Ethernet networkcomprises a communication failure, wherein said central processing unitcomprises configuration data within said configuration chart and aconfiguration switch internal to said central processing unit, andwherein the central processing unit in response to the configurationdata and said status bit is configured to direct the internalconfiguration switch to switch from said first VLAN to said second VLAN,wherein said embedded microprocessor is configured to accept programmingof polling characteristics for polling said at least one local networkdevice, and wherein said polling characteristics consist of a frequencyof polling of said at least one local network device, a number of timesfor sending said test message before reporting a failure, and a delaytime for waiting for a response to said test message.
 2. Thecommunications network of claim 1, wherein said network switch includes:a network port; a device port; and an Ethernet switch connected to saidnetwork port and said device port, wherein said Ethernet switch couplessaid network port to said device port.
 3. The communications network ofclaim 2, wherein said configuration switch is further configured tocontrol coupling of said network port to said device port within saidEthernet switch.
 4. The communications network of claim 1, wherein saidembedded microprocessor is configured to send said test message to saidat least one local network device multiple times at various timeintervals.
 5. A method of providing redundancy in a communicationsnetwork, said method comprising: providing a primary Ethernet network,an alternate Ethernet network, and a network switch comprising a centralprocessing unit internal to said network switch, wherein said centralprocessing unit is directly connected to said primary Ethernet networkand said alternate Ethernet network, wherein said central processingunit is configured to prevent communications between said primaryEthernet network and said alternate Ethernet network, wherein saidcentral processing unit comprises an embedded microprocessor, whereinsaid primary Ethernet network is configured to be connected to at leastone local network device through said embedded microprocessor, whereinsaid alternate Ethernet network is configured to be connected to said atleast one local network device through said embedded microprocessor,wherein said at least one local network device is not located withinsaid primary Ethernet network or said alternate Ethernet network,wherein said embedded microprocessor comprises a configuration chartinternal to said embedded microprocessor, wherein configuration chartcomprises connection rules associated with said primary Ethernet networkand said alternate Ethernet network, wherein said configuration chartcomprises a primary connection and an optional secondary connection forsaid at least one local network device, wherein said configuration chartcomprises an Internet protocol (IP) address or media access control(MAC) address of said at least one local network device, wherein saidcentral processing unit comprises configuration data within saidconfiguration chart and a configuration switch internal to said centralprocessing unit, wherein said primary Ethernet network is independentfrom said alternate Ethernet network, wherein said primary Ethernetnetwork is not connected said alternate Ethernet network, wherein saidprimary Ethernet network is configured to receive information from saidat least one local network device, wherein said alternate Ethernetnetwork is configured to receive said information from said localnetwork device, wherein said information is routed through said embeddedmicroprocessor, and wherein said primary Ethernet network in combinationwith said central processing unit and said at least one local networkdevice forms a first virtual local area network (VLAN), wherein saidalternate Ethernet network in combination with said central processingunit and said at least one local network device forms a second VLAN;accepting, by said embedded microprocessor, programming of pollingcharacteristics for polling said at least one local network device,wherein said polling characteristics consist of a frequency of pollingof said at least one local network device, a number of times for sendingsaid test message before reporting a failure, and a delay time forwaiting for a response to said test message; selectively enabling bysaid network switch, communication between said primary network and saidat least one local network device or between said alternate Ethernetnetwork and said at least one local network device, wherein said networkswitch does not enable communication between said primary network andsaid alternate network; sending, by said microprocessor, a test messageto said at least one local network device in order to determine anoperational status of said primary Ethernet network; indicating, by saidoperational status, that said primary Ethernet network comprises acommunication failure; setting, by said communications network, a statusbit in said microprocessor to indicate that said primary Ethernetnetwork comprises a communication failure; and directing, by the centralprocessing unit in response to the configuration data and said statusbit, the internal configuration switch to switch from said first VLAN tosaid second VLAN.
 6. The method of claim 5, wherein said network switchcomprises a network port, a device port, and an Ethernet switch, andwherein said method further comprises: connecting said at least oneEthernet switch to said network port and said device port, wherein saidEthernet switch couples said network port to said device port.
 7. Themethod of claim 6, wherein said configuration switch is configured tocontrol coupling of said network port to said device port within saidEthernet switch.
 8. The method of claim 5, further comprising: sending,by said embedded microprocessor, said test message to said at least onelocal network device multiple times at various time intervals.
 9. Anetwork switch comprising: a first plurality of communication ports,said first plurality of communication ports coupled to a primaryEthernet network and an alternate Ethernet network, wherein said primaryEthernet network is independent from said alternate Ethernet network,wherein said primary Ethernet network is not connected to said alternateEthernet network; a second plurality of communication ports, said secondplurality of communication ports coupled to one or more local networkdevices; a plurality of communication path combinations available insaid network switch, wherein each said communication path combination isselected from the group consisting of: the primary Ethernet network to afirst local network device; the primary Ethernet network to a secondlocal network device; the alternate Ethernet network to the first localnetwork device; and the alternate Ethernet network to the second localnetwork device; and a central processing unit internal to said networkswitch, wherein said central processing unit comprises an embeddedmicroprocessor, wherein said central processing unit is directlyconnected to said primary Ethernet network and said alternate Ethernetnetwork, wherein said central processing unit is configured to preventcommunications between said primary Ethernet network and said alternateEthernet network, wherein said primary Ethernet network is configured tobe connected to said first network device or said second network devicethrough said embedded microprocessor, wherein said alternate Ethernetnetwork is configured to be connected to said first network device orsaid second network device through said embedded microprocessor, whereinsaid first network device and said second network device are not locatedwithin said primary Ethernet network or said alternate Ethernet network,wherein said embedded microprocessor comprises a configuration chartinternal to said embedded microprocessor, wherein configuration chartcomprises connection rules associated with said primary Ethernet networkand said alternate Ethernet network, wherein said configuration chartcomprises a primary connection and an optional secondary connection forsaid at least one local network device, wherein said configuration chartcomprises an Internet protocol (IP) address or media access control(MAC) address of said at least one local network device, wherein saidprimary Ethernet network is configured to receive information from saidfirst local network device or said second local network device and saidnetwork switch, wherein said alternate Ethernet network is configured toreceive said information from said first local network device or saidsecond local network device and said network switch, wherein saidinformation is routed through said embedded microprocessor, wherein saidcentral processing unit comprises configuration data within saidconfiguration chart and a configuration switch internal to said centralprocessing unit, wherein said primary Ethernet network in combinationwith said central processing unit and said first local network deviceforms a first virtual local area network (VLAN), wherein said alternateEthernet network in combination with said central processing unit andsaid first local network device forms a second VLAN, wherein saidembedded microprocessor is configured to send a test message to saidfirst local network device in order to determine an operational statusof said primary Ethernet network, wherein said communications network isconfigured to set a status bit in said microprocessor if saidoperational status indicates that said primary Ethernet networkcomprises a communication failure, wherein said central processing unitcomprises configuration data and a configuration switch internal to saidcentral processing unit, and wherein the central processing unit inresponse to the configuration data and said status bit is configured todirect the internal configuration switch to switch virtual connectionsfrom the central processing unit to the primary Ethernet network or thealternate Ethernet network from said first VLAN to said second VLAN, andwherein said embedded microprocessor is configured to accept programmingof polling characteristics for polling said at least one local networkdevice, and wherein said polling characteristics consist of a frequencyof polling of said at least one local network device, a number of timesfor sending said test message before reporting a failure, and a delaytime for waiting for a response to said test message.
 10. The networkswitch of claim 9, wherein said network switch further comprises: asystem for monitoring a status of said primary Ethernet network and saidalternate Ethernet network; apparatus for detecting a failed network,said failed network being said primary Ethernet network that has failedor said alternate Ethernet network that has failed; a system for makingthe failed network an inactive network; a system for making theremaining network an active network, said remaining network being one ofsaid primary Ethernet network that has not failed or said alternateEthernet network that has not failed; and a system for reroutingcommunication, such that the communication, that was passed through thenetwork that has failed, is passed through the network that has notfailed.
 11. The network switch of claim 9, wherein said network switchfurther comprises: a programmable device, wherein said programmabledevice includes a memory storage system; a routing system for enablingat least one of said communication path combinations, wherein saidprogrammable device controls said routing system; and a system forprogramming said programmable device to disable at least one of saidplurality of communication path combinations.
 12. The network switch ofclaim 11, wherein: said programmable device includes operating software,said operating software responsive to communication from said primaryEthernet network or said alternate Ethernet network, from a remotedevice, or from a manual input device.
 13. The network switch of claim11, wherein said programmable device is said embedded microprocessorwithin said central processing unit.
 14. The network switch of claim 13,wherein: said microprocessor is connected to a port of the networkswitch; said primary Ethernet network and said alternate Ethernetnetwork are connected to said local network devices, wherein at leastone of said primary Ethernet network and said alternate Ethernet networkis enabled; and said embedded microprocessor is connected to at leasttwo restricted VLAN groups.
 15. The network switch of claim 13, whereinan IP address is assigned to the embedded microprocessor.
 16. Thenetwork switch of claim 9, wherein said network switch is an Ethernetdevice.
 17. The network switch of claim 16, wherein said network switchis a VLAN switch.
 18. The network switch of claim 9, further comprisinga network port connected to an internet connection module, said internetconnection module connecting said network switch to said primaryEthernet network and said alternate Ethernet network.
 19. The networkswitch of claim 9, further comprising device port connected to aninternet connection module, said internet connection module connectingsaid network switch to said primary Ethernet network and said alternateEthernet network.
 20. A method of network communication comprising:providing a first plurality of communication ports, said first pluralityof communication ports coupled to a primary Ethernet network and analternate Ethernet network, wherein said primary Ethernet network isindependent from said alternate Ethernet network, and wherein saidprimary Ethernet network is not connected to said alternate Ethernetnetwork; providing a second plurality of communication ports, saidsecond plurality of communication ports coupled to one or more localnetwork devices; providing a plurality of communication pathcombinations available in a network switch, wherein each saidcommunication path combination is selected from the group consisting of:the primary Ethernet network to a first local network device; theprimary Ethernet network to a second local network device; the alternateEthernet network to the first local network device; the alternateEthernet network to the second local network device; and providingwithin said network switch, a central processing unit internal to saidnetwork switch, wherein said central processing unit comprises anembedded microprocessor, wherein said central processing unit isdirectly connected to said primary Ethernet network and said alternateEthernet network, wherein said central processing unit is configured toprevent communications between said primary Ethernet network and saidalternate Ethernet network, wherein said primary Ethernet network isconfigured to be connected to said first network device or said secondnetwork device through said embedded microprocessor, wherein saidalternate Ethernet network is configured to be connected to said firstnetwork device or said second network device through said embeddedmicroprocessor, wherein said first network device and said secondnetwork device are not located within said primary Ethernet network orsaid alternate Ethernet network, wherein said embedded microprocessorcomprises a configuration chart internal to said embeddedmicroprocessor, wherein configuration chart comprises connection rulesassociated with said primary Ethernet network and said alternateEthernet network, wherein said configuration chart comprises a primaryconnection and an optional secondary connection for said at least onelocal network device, wherein said configuration chart comprises anInternet protocol (IP) address or media access control (MAC) address ofsaid at least one local network device, wherein said primary Ethernetnetwork is configured to receive information from said first localnetwork device or said second local network device and said networkswitch, wherein said alternate Ethernet network is configured to receivesaid information from said first local network device or said secondlocal network device and said network switch, wherein said informationis routed through said embedded microprocessor, wherein said centralprocessing unit comprises configuration data within said configurationchart and a configuration switch internal to said central processingunit, wherein said primary Ethernet network in combination with saidcentral processing unit and said first local network device forms afirst virtual local area network (VLAN), wherein said alternate Ethernetnetwork in combination with said central processing unit and said firstlocal network device forms a second VLAN, wherein said microprocessor isconfigured to send a test message to said first local network device inorder to determine an operational status of said primary Ethernetnetwork, wherein said communications network is configured to set astatus bit in said embedded microprocessor if said operational statusindicates that said primary Ethernet network comprises a communicationfailure, wherein said central processing unit comprises configurationdata and a configuration switch internal to said central processingunit, and wherein the central processing unit in response to theconfiguration data and said status bit is configured to direct theinternal configuration switch to switch virtual connections from thecentral processing unit to the primary Ethernet network or the alternateEthernet network from said first VLAN to said second VLAN, and whereinsaid embedded microprocessor is configured to accept programming ofpolling characteristics for polling said at least one local networkdevice, and wherein said polling characteristics consist of a frequencyof polling of said at least one local network device, a number of timesfor sending said test message before reporting a failure, and a delaytime for waiting for a response to said test message.
 21. The method ofclaim 20, wherein said network switch further comprises: a system formonitoring a status of said primary Ethernet network and said alternateEthernet network; a system for detecting a failed network, said failednetwork being said primary Ethernet network that has failed or saidalternate Ethernet network that has failed; a system for making thefailed network an inactive network; a system for making the remainingnetwork an active network, said remaining network being one of saidprimary Ethernet network that has not failed or said alternate Ethernetnetwork that has not failed; and a system for rerouting communication tothe network that has not failed.
 22. The method of claim 20, whereinsaid network switch further comprises: a programmable device, whereinsaid programmable device includes a memory storage system; a routingsystem for enabling at least one of said communication pathcombinations, wherein said programmable device controls said routingsystem; and a system for programming said programmable device to disableat least one of said plurality of communication path combinations. 23.The method of claim 22, wherein: said programmable device includesoperating software, said operating software responsive to communicationfrom said primary Ethernet network or said alternate Ethernet network,from a remote device, or from a manual input device.
 24. The method ofclaim 22, wherein said network switch is a VLAN switch.
 25. The methodof claim 22, wherein said programmable device is said embeddedmicroprocessor within said central processing unit.
 26. The method ofclaim 25, wherein: said embedded microprocessor is connected to a portof the network switch; said primary Ethernet network and said alternateEthernet network are connected to said local network devices, wherein atleast one of said primary Ethernet network and said alternate Ethernetnetwork is enabled; and said embedded microprocessor connected to atleast two restricted VLAN groups.
 27. The method of claim 25, wherein anIP address is assigned to the embedded microprocessor.
 28. The method ofclaim 20, wherein said network switch is an Ethernet device.
 29. Themethod of claim 20, further comprising providing an internet connection,said internet connection connecting said network switch to said primaryEthernet network and said alternate Ethernet network.
 30. The presentinvention provides a computer program product, comprising a computerreadable medium comprising a computer readable program code embodiedtherein, said computer readable program code adapted to implement amethod for providing redundancy in a communications network, said methodcomprising: providing a primary Ethernet network, an alternate Ethernetnetwork, and a network switch comprising a central processing unitinternal to said network switch, wherein said central processing unit isdirectly connected to said primary Ethernet network and said alternateEthernet network, wherein said central processing unit is configured toprevent communications between said primary Ethernet network and saidalternate Ethernet network, wherein said central processing unitcomprises an embedded microprocessor, wherein said primary Ethernetnetwork is configured to be connected to at least one local networkdevice through said embedded microprocessor, wherein said alternateEthernet network is configured to be connected to said at least onelocal network device through said embedded microprocessor, wherein saidat least one local network device is not located within said primaryEthernet network or said alternate Ethernet network, wherein saidembedded microprocessor comprises a configuration chart internal to saidembedded microprocessor, wherein configuration chart comprisesconnection rules associated with said primary Ethernet network and saidalternate Ethernet network, wherein said configuration chart comprisesan Internet protocol (IP) address or media access control (MAC) addressof said at least one local network device, wherein said centralprocessing unit comprises configuration data within said configurationchart and a configuration switch internal to said central processingunit, wherein said primary Ethernet network is independent from saidalternate Ethernet network, wherein said primary Ethernet network is notconnected said alternate Ethernet network, wherein said primary Ethernetnetwork is configured to receive information from said at least onelocal network device, wherein said alternate Ethernet network isconfigured to receive said information from said local network device,wherein said information is routed through said embedded microprocessor,and wherein said primary Ethernet network in combination with saidcentral processing unit and said at least one local network device formsa first virtual local area network (VLAN), wherein said alternateEthernet network in combination with said central processing unit andsaid at least one local network device forms a second VLAN; accepting,by said embedded microprocessor, programming of polling characteristicsfor polling said at least one local network device, wherein said pollingcharacteristics consist of a frequency of polling of said at least onelocal network device, a number of times for sending said test messagebefore reporting a failure, and a delay time for waiting for a responseto said test message; selectively enabling by said network switch,communication between said primary network and said at least one localnetwork device or between said alternate Ethernet network and said atleast one local network device, wherein said network switch does notenable communication between said primary network and said alternatenetwork; sending, by said microprocessor, a test message to said atleast one local network device in order to determine an operationalstatus of said primary Ethernet network; indicating, by said operationalstatus, that said primary Ethernet network comprises a communicationfailure; setting, by said communications network, a status bit in saidmicroprocessor to indicate that said primary Ethernet network comprisesa communication failure; and directing, by the central processing unitin response to the configuration data and said status bit, the internalconfiguration switch to switch from said first VLAN to said second VLAN.31. The computer program product of claim 30, wherein said networkswitch comprises a network port, a device port, and an Ethernet switch,and wherein said method further comprises: connecting said at least oneEthernet switch to said network port and said device port, wherein saidEthernet switch couples said network port to said device port.
 32. Thecomputer program product of claim 30, wherein said configuration switchis adapted to control coupling of said network port to said device portwithin said Ethernet switch.